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# -*- coding: utf-8 -*-
import hashlib
import struct
from foreign.client_handling.lazagne.config.crypto.pyaes.aes import AESModeOfOperationECB, AESModeOfOperationCBC
from foreign.client_handling.lazagne.config.winstructure import char_to_int
AES_BLOCK_SIZE = 16
def sha256(s):
"""Return SHA256 digest of the string `s`."""
return hashlib.sha256(s).digest()
def transform_key(key, seed, rounds):
"""Transform `key` with `seed` `rounds` times using AES ECB."""
# create transform cipher with transform seed
cipher = AESModeOfOperationECB(seed)
# transform composite key rounds times
for n in range(0, rounds):
key = b"".join([cipher.encrypt(key[i:i + AES_BLOCK_SIZE]) for i in range(0, len(key), AES_BLOCK_SIZE)])
# return hash of transformed key
return sha256(key)
def aes_cbc_decrypt(data, key, enc_iv):
"""Decrypt and return `data` with AES CBC."""
cipher = AESModeOfOperationCBC(key, iv=enc_iv)
return b"".join([cipher.decrypt(data[i:i + AES_BLOCK_SIZE]) for i in range(0, len(data), AES_BLOCK_SIZE)])
def aes_cbc_encrypt(data, key, enc_iv):
cipher = AESModeOfOperationCBC(key, iv=enc_iv)
return b"".join([cipher.encrypt(data[i:i + AES_BLOCK_SIZE]) for i in range(0, len(data), AES_BLOCK_SIZE)])
def unpad(data):
extra = char_to_int(data[-1])
return data[:len(data) - extra]
def pad(s):
n = AES_BLOCK_SIZE - len(s) % AES_BLOCK_SIZE
return s + n * struct.pack('b', n)
def xor(aa, bb):
"""Return a bytearray of a bytewise XOR of `aa` and `bb`."""
result = bytearray()
for a, b in zip(bytearray(aa), bytearray(bb)):
result.append(a ^ b)
return result
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